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man(1) - phpMan

Command: man perldoc info search(apropos)  


MAN(1)                                  Manual pager utils                                 MAN(1)



NAME
       man - an interface to the on-line reference manuals

SYNOPSIS
       man  [-C  file]  [-d]  [-D]  [--warnings[=warnings]]  [-R  encoding]  [-L locale] [-m sys‐
       tem[,...]] [-M path] [-S list] [-e extension] [-i|-I] [--regex|--wildcard]  [--names-only]
       [-a]  [-u]  [--no-subpages]  [-P  pager] [-r prompt] [-7] [-E encoding] [--no-hyphenation]
       [--no-justification] [-p string] [-t] [-T[device]] [-H[browser]] [-X[dpi]] [-Z] [[section]
       page ...] ...
       man -k [apropos options] regexp ...
       man -K [-w|-W] [-S list] [-i|-I] [--regex] [section] term ...
       man -f [whatis options] page ...
       man  -l  [-C  file] [-d] [-D] [--warnings[=warnings]] [-R encoding] [-L locale] [-P pager]
       [-r prompt] [-7] [-E encoding] [-p string] [-t] [-T[device]] [-H[browser]] [-X[dpi]]  [-Z]
       file ...
       man -w|-W [-C file] [-d] [-D] page ...
       man -c [-C file] [-d] [-D] page ...
       man [-?V]

DESCRIPTION
       man is the system's manual pager.  Each page argument given to man is normally the name of
       a program, utility or function.  The manual page associated with each of  these  arguments
       is then found and displayed.  A section, if provided, will direct man to look only in that
       section of the manual.  The default action is to search in all of the  available  sections
       following a pre-defined order ("1 n l 8 3 2 3posix 3pm 3perl 5 4 9 6 7" by default, unless
       overridden by the SECTION directive in /etc/manpath.config), and to show  only  the  first
       page found, even if page exists in several sections.

       The  table  below  shows  the section numbers of the manual followed by the types of pages
       they contain.


       1   Executable programs or shell commands
       2   System calls (functions provided by the kernel)
       3   Library calls (functions within program libraries)
       4   Special files (usually found in /dev)
       5   File formats and conventions eg /etc/passwd
       6   Games
       7   Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)
       8   System administration commands (usually only for root)
       9   Kernel routines [Non standard]

       A manual page consists of several sections.

       Conventional section names include NAME, SYNOPSIS,  CONFIGURATION,  DESCRIPTION,  OPTIONS,
       EXIT STATUS,  RETURN VALUE,  ERRORS,  ENVIRONMENT,  FILES, VERSIONS, CONFORMING TO, NOTES,
       BUGS, EXAMPLE, AUTHORS, and SEE ALSO.

       The following conventions apply to the SYNOPSIS section and can be  used  as  a  guide  in
       other sections.


       bold text          type exactly as shown.
       italic text        replace with appropriate argument.
       [-abc]             any or all arguments within [ ] are optional.
       -a|-b              options delimited by | cannot be used together.
       argument ...       argument is repeatable.
       [expression] ...   entire expression within [ ] is repeatable.

       Exact  rendering  may vary depending on the output device.  For instance, man will usually
       not be able to render italics when running in a terminal, and will  typically  use  under‐
       lined or coloured text instead.

       The  command  or function illustration is a pattern that should match all possible invoca‐
       tions.  In some cases it is advisable to illustrate several exclusive  invocations  as  is
       shown in the SYNOPSIS section of this manual page.

EXAMPLES
       man ls
           Display the manual page for the item (program) ls.

       man -a intro
           Display,  in  succession, all of the available intro manual pages contained within the
           manual.  It is possible to quit between successive displays or skip any of them.

       man -t alias | lpr -Pps
           Format the manual page referenced by `alias', usually a shell manual  page,  into  the
           default troff or groff format and pipe it to the printer named ps.  The default output
           for groff is usually PostScript.  man --help should advise as to  which  processor  is
           bound to the -t option.

       man -l -Tdvi ./foo.1x.gz > ./foo.1x.dvi
           This  command will decompress and format the nroff source manual page ./foo.1x.gz into
           a device independent (dvi) file.  The redirection is necessary as the -T  flag  causes
           output to be directed to stdout with no pager.  The output could be viewed with a pro‐
           gram such as xdvi or further processed into PostScript using a program such as dvips.

       man -k printf
           Search the short descriptions and manual page names for the keyword printf as  regular
           expression.  Print out any matches.  Equivalent to apropos -r printf.

       man -f smail
           Lookup  the  manual  pages referenced by smail and print out the short descriptions of
           any found.  Equivalent to whatis -r smail.

OVERVIEW
       Many options are available to man in order to give as much flexibility as possible to  the
       user.   Changes can be made to the search path, section order, output processor, and other
       behaviours and operations detailed below.

       If set, various environment variables are interrogated to determine the operation of  man.
       It  is possible to set the `catch all' variable $MANOPT to any string in command line for‐
       mat with the exception that any spaces used as  part  of  an  option's  argument  must  be
       escaped  (preceded  by a backslash).  man will parse $MANOPT prior to parsing its own com‐
       mand line.  Those options requiring an argument will be overridden  by  the  same  options
       found  on  the command line.  To reset all of the options set in $MANOPT, -D can be speci‐
       fied as the initial command line option.  This  will  allow  man  to  `forget'  about  the
       options specified in $MANOPT although they must still have been valid.

       The manual pager utilities packaged as man-db make extensive use of index database caches.
       These caches contain information such as where each  manual  page  can  be  found  on  the
       filesystem  and what its whatis (short one line description of the man page) contains, and
       allow man to run faster than if it had to search the filesystem  each  time  to  find  the
       appropriate  manual  page.   If  requested  using  the -u option, man will ensure that the
       caches remain consistent, which can obviate the need to manually run  software  to  update
       traditional whatis text databases.

       If  man  cannot find a mandb initiated index database for a particular manual page hierar‐
       chy, it will still search for the requested manual pages, although file globbing  will  be
       necessary to search within that hierarchy.  If whatis or apropos fails to find an index it
       will try to extract information from a traditional whatis database instead.

       These utilities support compressed source nroff files having, by default,  the  extensions
       of .Z, .z and .gz.  It is possible to deal with any compression extension, but this infor‐
       mation must be known at compile time.  Also, by default, any cat pages produced  are  com‐
       pressed  using  gzip.   Each  `global'  manual  page  hierarchy  such as /usr/share/man or
       /usr/X11R6/man may have any directory as its cat page hierarchy.   Traditionally  the  cat
       pages  are stored under the same hierarchy as the man pages, but for reasons such as those
       specified in the File Hierarchy Standard (FHS), it may be better to store them  elsewhere.
       For  details  on  how  to do this, please read manpath(5).  For details on why to do this,
       read the standard.

       International support is available with this package.  Native language  manual  pages  are
       accessible  (if  available  on your system) via use of locale functions.  To activate such
       support, it is necessary to set either $LC_MESSAGES, $LANG  or  another  system  dependent
       environment  variable to your language locale, usually specified in the POSIX 1003.1 based
       format:

       <language>[_<territory>[.<character-set>[,<version>]]]

       If the desired page is available in your locale, it will be displayed in lieu of the stan‐
       dard (usually American English) page.

       Support  for  international message catalogues is also featured in this package and can be
       activated in the same way, again if available.  If you find that the manual pages and mes‐
       sage  catalogues  supplied with this package are not available in your native language and
       you would like to supply them, please contact the maintainer who will be coordinating such
       activity.

       For  information regarding other features and extensions available with this manual pager,
       please read the documents supplied with the package.

DEFAULTS
       man will search for the desired manual pages within the index database caches. If  the  -u
       option is given, a cache consistency check is performed to ensure the databases accurately
       reflect the filesystem.  If this option is always given, it is not generally necessary  to
       run  mandb  after  the caches are initially created, unless a cache becomes corrupt.  How‐
       ever, the cache consistency check can be slow on systems with many manual pages installed,
       so  it  is not performed by default, and system administrators may wish to run mandb every
       week or so to keep the database caches fresh.  To forestall problems  caused  by  outdated
       caches,  man  will fall back to file globbing if a cache lookup fails, just as it would if
       no cache was present.

       Once a manual page has been located, a check is performed to find out if a  relative  pre‐
       formatted  `cat' file already exists and is newer than the nroff file.  If it does and is,
       this preformatted file is (usually) decompressed and then displayed, via use of  a  pager.
       The  pager  can  be  specified in a number of ways, or else will fall back to a default is
       used (see option -P for details).  If no cat is found or is older than the nroff file, the
       nroff is filtered through various programs and is shown immediately.

       If a cat file can be produced (a relative cat directory exists and has appropriate permis‐
       sions), man will compress and store the cat file in the background.

       The filters are deciphered by a number of means.  Firstly, the command line option  -p  or
       the environment variable $MANROFFSEQ is interrogated.  If -p was not used and the environ‐
       ment variable was not set, the initial line of the nroff file is parsed for a preprocessor
       string.  To contain a valid preprocessor string, the first line must resemble

       '\" <string>

       where string can be any combination of letters described by option -p below.

       If none of the above methods provide any filter information, a default set is used.

       A  formatting  pipeline  is  formed  from  the filters and the primary formatter (nroff or
       [tg]roff with -t) and executed.  Alternatively, if an executable  program  mandb_nfmt  (or
       mandb_tfmt  with  -t) exists in the man tree root, it is executed instead.  It gets passed
       the manual source file, the preprocessor string, and optionally the device specified  with
       -T or -E as arguments.

OPTIONS
       Non  argument options that are duplicated either on the command line, in $MANOPT, or both,
       are not harmful.  For options that require an argument, each duplication will override the
       previous argument value.

   General options
       -C file, --config-file=file
              Use this user configuration file rather than the default of ~/.manpath.

       -d, --debug
              Print debugging information.

       -D, --default
              This  option is normally issued as the very first option and resets man's behaviour
              to its default.  Its use is to reset those  options  that  may  have  been  set  in
              $MANOPT.  Any options that follow -D will have their usual effect.

       --warnings[=warnings]
              Enable  warnings  from  groff.   This  may  be used to perform sanity checks on the
              source text of manual pages.  warnings is a comma-separated list of warning  names;
              if it is not supplied, the default is "mac".  See the “Warnings” node in info groff
              for a list of available warning names.

   Main modes of operation
       -f, --whatis
              Equivalent to whatis.  Display a short description from the manual page, if  avail‐
              able.  See whatis(1) for details.

       -k, --apropos
              Equivalent  to apropos.  Search the short manual page descriptions for keywords and
              display any matches.  See apropos(1) for details.

       -K, --global-apropos
              Search for text in all manual pages.  This is a brute-force search, and  is  likely
              to take some time; if you can, you should specify a section to reduce the number of
              pages that need to be searched.  Search terms may be simple strings (the  default),
              or regular expressions if the --regex option is used.

       -l, --local-file
              Activate  `local' mode.  Format and display local manual files instead of searching
              through the system's manual collection.  Each manual page argument will  be  inter‐
              preted as an nroff source file in the correct format.  No cat file is produced.  If
              '-' is listed as one of the arguments, input will be taken from stdin.   When  this
              option  is not used, and man fails to find the page required, before displaying the
              error message, it attempts to act as if this option was supplied, using the name as
              a filename and looking for an exact match.

       -w, --where, --path, --location
              Don't actually display the manual pages, but do print the location(s) of the source
              nroff files that would be formatted.

       -W, --where-cat, --location-cat
              Don't actually display the manual pages, but do print the location(s)  of  the  cat
              files  that  would be displayed.  If -w and -W are both specified, print both sepa‐
              rated by a space.

       -c, --catman
              This option is not for general use and should only be used by the catman program.

       -R encoding, --recode=encoding
              Instead of formatting the manual page in the usual way, output its source converted
              to  the  specified  encoding.  If you already know the encoding of the source file,
              you can also use manconv(1) directly.  However, this option allows you  to  convert
              several  manual  pages  to a single encoding without having to explicitly state the
              encoding of each, provided that they were already installed in a structure  similar
              to a manual page hierarchy.

   Finding manual pages
       -L locale, --locale=locale
              man  will normally determine your current locale by a call to the C function setlo‐
              cale(3)  which  interrogates  various  environment  variables,  possibly  including
              $LC_MESSAGES  and  $LANG.   To  temporarily override the determined value, use this
              option to supply a locale string directly to man.   Note  that  it  will  not  take
              effect until the search for pages actually begins.  Output such as the help message
              will always be displayed in the initially determined locale.

       -m system[,...], --systems=system[,...]
              If this system has access to other operating system's manual  pages,  they  can  be
              accessed  using  this option.  To search for a manual page from NewOS's manual page
              collection, use the option -m NewOS.

              The system specified can be a  combination  of  comma  delimited  operating  system
              names.   To include a search of the native operating system's manual pages, include
              the system name man in the argument string.  This option will override the  $SYSTEM
              environment variable.

       -M path, --manpath=path
              Specify  an alternate manpath to use.  By default, man uses manpath derived code to
              determine the path to search.  This option overrides the $MANPATH environment vari‐
              able and causes option -m to be ignored.

              A  path  specified  as a manpath must be the root of a manual page hierarchy struc‐
              tured into sections as described in the man-db manual (under "The manual page  sys‐
              tem").  To view manual pages outside such hierarchies, see the -l option.

       -S list, -s list, --sections=list
              List  is  a  colon-  or comma-separated list of `order specific' manual sections to
              search.  This option overrides the $MANSECT environment variable.  (The -s spelling
              is for compatibility with System V.)

       -e sub-extension, --extension=sub-extension
              Some  systems incorporate large packages of manual pages, such as those that accom‐
              pany the Tcl package, into the main manual page hierarchy.  To get around the prob‐
              lem  of  having  two manual pages with the same name such as exit(3), the Tcl pages
              were usually all assigned to section l.  As this is unfortunate, it is now possible
              to  put  the  pages in the correct section, and to assign a specific `extension' to
              them, in this case, exit(3tcl).  Under normal operation, man will  display  exit(3)
              in  preference  to  exit(3tcl).  To negotiate this situation and to avoid having to
              know which section the page you require resides in, it is now possible to give  man
              a sub-extension string indicating which package the page must belong to.  Using the
              above example, supplying the option -e tcl to man will restrict the search to pages
              having an extension of *tcl.

       -i, --ignore-case
              Ignore case when searching for manual pages.  This is the default.

       -I, --match-case
              Search for manual pages case-sensitively.

       --regex
              Show  all  pages with any part of either their names or their descriptions matching
              each page argument as a regular expression, as with  apropos(1).   Since  there  is
              usually  no  reasonable  way  to  pick  a  "best" page when searching for a regular
              expression, this option implies -a.

       --wildcard
              Show all pages with any part of either their names or their  descriptions  matching
              each page argument using shell-style wildcards, as with apropos(1) --wildcard.  The
              page argument must match the entire name or description, or match  on  word  bound‐
              aries  in  the  description.   Since  there  is usually no reasonable way to pick a
              "best" page when searching for a wildcard, this option implies -a.

       --names-only
              If the --regex or --wildcard option is  used,  match  only  page  names,  not  page
              descriptions, as with whatis(1).  Otherwise, no effect.

       -a, --all
              By  default, man will exit after displaying the most suitable manual page it finds.
              Using this option forces man to display all the manual pages with names that  match
              the search criteria.

       -u, --update
              This  option  causes man to perform an `inode level' consistency check on its data‐
              base caches to ensure that they are an accurate representation of  the  filesystem.
              It will only have a useful effect if man is installed with the setuid bit set.

       --no-subpages
              By  default, man will try to interpret pairs of manual page names given on the com‐
              mand line as equivalent to a single manual page name  containing  a  hyphen  or  an
              underscore.   This  supports the common pattern of programs that implement a number
              of subcommands, allowing them to provide manual pages for each that can be accessed
              using  similar  syntax  as would be used to invoke the subcommands themselves.  For
              example:

                $ man -aw git diff
                /usr/share/man/man1/git-diff.1.gz

              To disable this behaviour, use the --no-subpages option.

                $ man -aw --no-subpages git diff
                /usr/share/man/man1/git.1.gz
                /usr/share/man/man3/Git.3pm.gz
                /usr/share/man/man1/diff.1.gz

   Controlling formatted output
       -P pager, --pager=pager
              Specify which output pager to use.  By default, man uses  pager  -s.   This  option
              overrides  the  $MANPAGER  environment variable, which in turn overrides the $PAGER
              environment variable.  It is not used in conjunction with -f or -k.

              The value may be a simple command name or a command with  arguments,  and  may  use
              shell quoting (backslashes, single quotes, or double quotes).  It may not use pipes
              to connect multiple commands; if you need that, use a  wrapper  script,  which  may
              take the file to display either as an argument or on standard input.

       -r prompt, --prompt=prompt
              If  a  recent  version  of  less  is used as the pager, man will attempt to set its
              prompt and some sensible options.  The default prompt looks like

               Manual page name(sec) line x

              where name denotes the manual page name, sec denotes the section it was found under
              and  x  the  current  line number.  This is achieved by using the $LESS environment
              variable.

              Supplying -r with a string will override this default.  The string may contain  the
              text  $MAN_PN which will be expanded to the name of the current manual page and its
              section name surrounded by `(' and `)'.  The string used  to  produce  the  default
              could be expressed as

              \ Manual\ page\ \$MAN_PN\ ?ltline\ %lt?L/%L.:
              byte\ %bB?s/%s..?\ (END):?pB\ %pB\\%..
              (press h for help or q to quit)

              It is broken into three lines here for the sake of readability only.  For its mean‐
              ing see the less(1) manual page.  The prompt  string  is  first  evaluated  by  the
              shell.   All  double  quotes,  back-quotes  and  backslashes  in the prompt must be
              escaped by a preceding backslash.  The prompt string may end in an escaped $  which
              may be followed by further options for less.  By default man sets the -ix8 options.

              The  $MANLESS  environment  variable  described  below may be used to set a default
              prompt string if none is supplied on the command line.

       -7, --ascii
              When viewing a pure ascii(7) manual page on a 7 bit terminal or terminal  emulator,
              some  characters may not display correctly when using the latin1(7) device descrip‐
              tion with GNU nroff.  This option allows pure ascii manual pages to be displayed in
              ascii  with the latin1 device.  It will not translate any latin1 text.  The follow‐
              ing table shows the translations performed: some parts of it may only be  displayed
              properly when using GNU nroff's latin1(7) device.


              Description           Octal   latin1   ascii
              ─────────────────────────────────────────────
              continuation hyphen    255      ‐        -
              bullet (middle dot)    267      ·        o
              acute accent           264      ´        '
              multiplication sign    327      ×        x

              If  the  latin1  column  displays correctly, your terminal may be set up for latin1
              characters and this option is not necessary.  If the latin1 and ascii  columns  are
              identical,  you  are reading this page using this option or man did not format this
              page using the latin1 device description.  If the latin1 column is missing or  cor‐
              rupt, you may need to view manual pages with this option.

              This  option is ignored when using options -t, -H, -T, or -Z and may be useless for
              nroff other than GNU's.

       -E encoding, --encoding=encoding
              Generate output for a character encoding other than the default.  For backward com‐
              patibility,  encoding may be an nroff device such as ascii, latin1, or utf8 as well
              as a true character encoding such as UTF-8.

       --no-hyphenation, --nh
              Normally, nroff will automatically hyphenate text at line breaks even in words that
              do  not  contain  hyphens,  if  it is necessary to do so to lay out words on a line
              without excessive spacing.  This option disables automatic  hyphenation,  so  words
              will only be hyphenated if they already contain hyphens.

              If  you are writing a manual page and simply want to prevent nroff from hyphenating
              a word at an inappropriate point, do not use this option,  but  consult  the  nroff
              documentation  instead;  for  instance,  you can put "\%" inside a word to indicate
              that it may be hyphenated at that point, or put "\%" at the start of a word to pre‐
              vent it from being hyphenated.

       --no-justification, --nj
              Normally,  nroff will automatically justify text to both margins.  This option dis‐
              ables full justification, leaving justified only  to  the  left  margin,  sometimes
              called "ragged-right" text.

              If  you  are writing a manual page and simply want to prevent nroff from justifying
              certain paragraphs, do not use this option, but  consult  the  nroff  documentation
              instead;  for  instance, you can use the ".na", ".nf", ".fi", and ".ad" requests to
              temporarily disable adjusting and filling.

       -p string, --preprocessor=string
              Specify the sequence of preprocessors to run before nroff or troff/groff.  Not  all
              installations will have a full set of preprocessors.  Some of the preprocessors and
              the letters used to designate them are: eqn (e), grap (g), pic (p), tbl (t), vgrind
              (v), refer (r).  This option overrides the $MANROFFSEQ environment variable.  zsoe‐
              lim is always run as the very first preprocessor.

       -t, --troff
              Use groff -mandoc to format the manual page to stdout.  This option is not required
              in conjunction with -H, -T, or -Z.

       -T[device], --troff-device[=device]
              This option is used to change groff (or possibly troff's) output to be suitable for
              a device  other  than  the  default.   It  implies  -t.   Examples  (provided  with
              Groff-1.17) include dvi, latin1, ps, utf8, X75 and X100.

       -H[browser], --html[=browser]
              This  option  will cause groff to produce HTML output, and will display that output
              in a web browser.  The choice of browser is  determined  by  the  optional  browser
              argument if one is provided, by the $BROWSER environment variable, or by a compile-
              time default if that is unset (usually lynx).  This option  implies  -t,  and  will
              only work with GNU troff.

       -X[dpi], --gxditview[=dpi]
              This  option displays the output of groff in a graphical window using the gxditview
              program.  The dpi (dots per inch) may be 75, 75-12, 100, or 100-12,  defaulting  to
              75;  the  -12  variants  use a 12-point base font.  This option implies -T with the
              X75, X75-12, X100, or X100-12 device respectively.

       -Z, --ditroff
              groff will run troff and then use an appropriate post-processor to  produce  output
              suitable  for  the chosen device.  If groff -mandoc is groff, this option is passed
              to groff and will suppress the use of a post-processor.  It implies -t.

   Getting help
       -?, --help
              Print a help message and exit.

       --usage
              Print a short usage message and exit.

       -V, --version
              Display version information.

EXIT STATUS
       0      Successful program execution.

       1      Usage, syntax or configuration file error.

       2      Operational error.

       3      A child process returned a non-zero exit status.

       16     At least one of the pages/files/keywords didn't exist or wasn't matched.

ENVIRONMENT
       MANPATH
              If $MANPATH is set, its value is used as the path to search for manual pages.

       MANROFFOPT
              The contents of $MANROFFOPT are added to the command line every  time  man  invokes
              the formatter (nroff, troff, or groff).

       MANROFFSEQ
              If  $MANROFFSEQ  is set, its value is used to determine the set of preprocessors to
              pass each manual page through.  The default preprocessor list is system dependent.

       MANSECT
              If $MANSECT is set, its value is a colon-delimited list of sections and it is  used
              to  determine which manual sections to search and in what order.  The default is "1
              n l 8 3 2 3posix 3pm 3perl 5 4 9 6 7", unless overridden by the  SECTION  directive
              in /etc/manpath.config.

       MANPAGER, PAGER
              If  $MANPAGER or $PAGER is set ($MANPAGER is used in preference), its value is used
              as the name of the program used to display the manual page.  By default,  pager  -s
              is used.

              The  value  may  be  a simple command name or a command with arguments, and may use
              shell quoting (backslashes, single quotes, or double quotes).  It may not use pipes
              to  connect  multiple  commands;  if you need that, use a wrapper script, which may
              take the file to display either as an argument or on standard input.

       MANLESS
              If $MANLESS is set, its value will be used as the default  prompt  string  for  the
              less pager, as if it had been passed using the -r option (so any occurrences of the
              text $MAN_PN will be expanded in the same way).  For example, if you  want  to  set
              the   prompt  string  unconditionally  to  “my  prompt  string”,  set  $MANLESS  to
              ‘-Psmy prompt string’.  Using the -r option overrides this environment variable.

       BROWSER
              If $BROWSER is set, its value is a colon-delimited list of commands, each of  which
              in  turn is used to try to start a web browser for man --html.  In each command, %s
              is replaced by a filename containing the HTML output from groff, %% is replaced  by
              a single percent sign (%), and %c is replaced by a colon (:).

       SYSTEM If  $SYSTEM is set, it will have the same effect as if it had been specified as the
              argument to the -m option.

       MANOPT If $MANOPT is set, it will be parsed prior to man's command line and is expected to
              be in a similar format.  As all of the other man specific environment variables can
              be expressed as command line options, and are thus candidates for being included in
              $MANOPT  it  is  expected  that  they  will become obsolete.  N.B.  All spaces that
              should be interpreted as part of an option's argument must be escaped.

       MANWIDTH
              If $MANWIDTH is set, its value is used as the line length for  which  manual  pages
              should  be formatted.  If it is not set, manual pages will be formatted with a line
              length appropriate to the  current  terminal  (using  the  value  of  $COLUMNS,  an
              ioctl(2)  if  available, or falling back to 80 characters if neither is available).
              Cat pages will only be saved when the default formatting can be used, that is  when
              the terminal line length is between 66 and 80 characters.

       MAN_KEEP_FORMATTING
              Normally,  when  output is not being directed to a terminal (such as to a file or a
              pipe), formatting characters are discarded to make it easier  to  read  the  result
              without  special  tools.   However, if $MAN_KEEP_FORMATTING is set to any non-empty
              value, these formatting characters are retained.  This may be useful  for  wrappers
              around man that can interpret formatting characters.

       MAN_KEEP_STDERR
              Normally,  when  output  is  being directed to a terminal (usually to a pager), any
              error output from the command used to produce formatted versions of manual pages is
              discarded  to  avoid  interfering with the pager's display.  Programs such as groff
              often produce relatively minor error messages about typographical problems such  as
              poor  alignment,  which  are unsightly and generally confusing when displayed along
              with the manual page.  However,  some  users  want  to  see  them  anyway,  so,  if
              $MAN_KEEP_STDERR  is  set to any non-empty value, error output will be displayed as
              usual.

       LANG, LC_MESSAGES
              Depending on system and implementation, either or both of  $LANG  and  $LC_MESSAGES
              will be interrogated for the current message locale.  man will display its messages
              in that locale (if available).  See setlocale(3) for precise details.

FILES
       /etc/manpath.config
              man-db configuration file.

       /usr/share/man
              A global manual page hierarchy.

       /usr/share/man/index.(bt|db|dir|pag)
              A traditional global index database cache.

       /var/cache/man/index.(bt|db|dir|pag)
              An FHS compliant global index database cache.

SEE ALSO
       apropos(1), groff(1), less(1), manpath(1), nroff(1), troff(1), whatis(1), zsoelim(1), set‐
       locale(3),  manpath(5), ascii(7), latin1(7), man(7), catman(8), mandb(8), the man-db pack‐
       age manual, FSSTND

HISTORY
       1990, 1991 – Originally written by John W. Eaton (jwe AT che.edu).

       Dec 23 1992: Rik Faith (faith AT cs.edu) applied bug fixes  supplied  by  Willem  Kasdorp
       (wkasdo AT nikhefk.nl).

       30th  April 1994 – 23rd February 2000: Wilf. (G.Wilford AT ee.uk) has been develop‐
       ing and maintaining this package with the help of a few dedicated people.

       30th October 1996 – 30th March 2001: Fabrizio Polacco <fpolacco AT debian.org> maintained and
       enhanced this package for the Debian project, with the help of all the community.

       31st  March  2001  – present day: Colin Watson <cjwatson AT debian.org> is now developing and
       maintaining man-db.



2.7.0.2                                     2014-09-28                                     MAN(1)


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